The best tool ever for programmers!

= memcheck =

You can prove if your program has memleaks, do I need to tell more?
valgrind --leak-check=full --show-reachable=yes

= massif =

http://valgrind.org/docs/manual/ms-manual.html
valgrind --tool=massif
ms_print massif.out.12345

= kcachegrind =
valgrind --tool=callgrind
kcachegrind callgrind.out.*